Effect of prostaglandin E2 on PZ-peptidase and several other peptidase activities in a clonal osteoblast-like cell line derived from newborn mouse calvaria.

The effects of prostaglandin E2(PGE2) on the degradation of collagen and non-collagenous peptides in clonal osteoblastic MC3T3-E1 cells were investigated by using highly sensitive assay methods for PZ-peptidase, collagenase-like peptidase (CL-peptidase), dipeptidyl-aminopeptidase (DAP), leucine aminopeptidase (LAP), and post-proline cleaving enzyme (PPCE). PGE2, at concentrations of 0.1 to 4.0 micrograms/ml, doubled the PZ-peptidase and CL-peptidase activities in the cells on 24 h culturing in a dose-dependent manner. PGE2, at a concentration of 2.0 micrograms/ml, enhanced the specific activities of PZ-peptidase, CL-peptidase, DAP, LAP, and PPCE for 75 h after the start of PGE2 stimulation. The time dependent changes in PZ-peptidase and CL-peptidase activities showed similar patterns, and 3- and 2-fold increases were seen after 48 h, respectively. The protein and DNA contents gradually increased after addition of PGE2. Since the PZ-peptidase and CL-peptidase, involved in degradation of collagen peptides, were significantly induced by PGE2 in comparison with LAP and PPCE, involved in the degradation of non-collagenous peptides, these results show that PGE2 specifically stimulates induction of collagen catabolizing enzymes in clonal osteoblasts.